This invention relates to a data recording apparatus, such as a hard disk drive apparatus. More particularly, this invention relates to a data re-assign method and its process when a sector from/to which read/write of data is difficult exists on a data track of a disk-shaped recording medium.
A hard disk drive apparatus is one of currently the most widespread external storage apparatuses for a computer apparatus. As well known, in a hard disk (also called a magnetic disk), which is a recording medium of the hard disk drive apparatus, sectors are made as the minimum recording units, which are obtained by partitioning a disk surface to tracks in the form of tree rings and further by radially separating the tracks.
All of these tracks are not always free from errors, and bad sectors from/to which data cannot be read/written may sometimes exist due to a scratch on the hard disk surface and adhesion of dust thereon. When the bad sectors are discovered in the manufacturing process of the hard disk, alternative sectors replacing the bad sectors that have occurred are allocated. Moreover, the bad sectors do not occur limited in the manufacturing process, but may sometimes occur during the use of the hard disk (product) after shipment thereof. In this case also, the alternative sectors replacing the bad sectors that have occurred are allocated. Allocation of the sectors in the manufacturing process of the product in a manner that only good sectors are used is referred to as “assign,” and allocation of the alternative sectors after the shipment of the product is referred to as “re-assign.”
The conventional hard disk drive apparatus is configured, when an access (read/write) from a host to a predetermined sector of the hard disk is difficult, to perform the re-assign (allocation of the alternative sectors) and to start an access to the next sector waiting for an end of the re-assign, that is, a completion of the data write to the alternative sectors.
However, the access to the next sector cannot be started until the re-assign is finished if the conventional technique as described above is used. Therefore, a technical problem has been seen, that latency occurs to bring about an instantaneous lowering in performance of the hard disk drive apparatus. Particularly, if the execution process of the re-assign becomes complicated, the above-described tendency becomes significant.